1. Field of Invention
The present invention generally relates to flash storage systems and devices, and more particularly to wear-leveling in flash storage systems and devices.
2. Description of Related Art
A typical flash storage device includes a controller that writes data to storage blocks of the flash storage device and reads data from these storage blocks. In a write operation to a storage block, the controller erases the storage block before data is written to that storage block. Eventually, after a sufficient number of erasures of the storage block, the storage block becomes defective and the controller replaces the defective storage block with a spare storage block in the flash storage device.
Wear in a storage block is determined by the number of erasures of the storage block. Some flash storage devices include a counter for each storage block for maintaining a count of erasures of the storage block. The controller uses the counter to perform wear-leveling in the flash storage device. In this process, the controller counts the number of erasures of each storage block and attempts to write data to those storage blocks that have a lower erasure count than the erasure count of other storage blocks. In this way, the lifetimes of individual storage blocks in the flash storage device, as well as the lifetime of the flash storage device, is increased. Because, each of the counters typically has a number of bits sufficient to count up to a predicted number of erasures before the storage block becomes defective, the counters consume significant area and power in a flash storage device.
In light of the above, a need exists for an improved system and method of performing wear-leveling in flash storage systems and devices.